This multi-center study will attempt to prevent the development of NIDDM in 200 subjects impaired glucose tolerance. This is a four-arm trial: usual care lifestyle plus placebo for pharmacological therapy; intensive lifestyle (special diet and exercise) plus placebo for pharmacological therapy; usual care lifestyle and Metformin; usual care lifestyle and Troglitazone The primary endpoint will be the development of NIDDM. Secondary endpoints include changes in lipids, lipoproteins, andle/arm blood pressure ratio, urinary albumin and carotid wall thickness.